All-digital cancellation technique to mitigate self-jamming in uplink carrier aggregation in cellular handsets

Abstract

Future handsets employing uplink carrier aggregation to increase transmit data rates will experience severe degradation in receiver sensitivity due to intermodulation products created by the nonlinearity of switches and duplexers in the RF front end for a number of LTE band combinations. To maintain the same receiver sensitivity an all-digital cancellation algorithm is proposed that relies solely on the digital representation of the signals, a peak covariance search for time alignment, and a recursive least squares (RLS) adaptive filter. This technique provides up to 20 dB improvement of signal-to-interference-plus-noise ratio (SINR), for 5-MHz LTE signals.